Carbon nanotubes were discovered in 1991 by Iijima on the negative electrode during the direct current arching of graphite for the preparation of fullerenes. Nanotubes are concentric graphitic cylinders closed at either end due to the presence of five membered rings. Carbon nanotubes can either be multi walled or single walled. Multi-walled nanotubes (MWNT) have a central tubule surrounding graphitic layers whereas single walled nanotubes (SWNT) have only one tubule and no graphitic layers.
Single-walled carbon nanotubes (SWNT) have moved to the forefront of present and future nanoscale discoveries that will serve as a portal into the enhancement of modern technology. Many different applications of carbon nanotubes have recently been developed, including the use of nanoscale transistors and chemical sensors. Carbon nanotubes exhibit a high aspect ratio, mechanical strength, and high moduli. These properties have spurred an interest in fabricating polymer-nanotube composites.
Composites are developed to achieve desired properties that cannot be obtained from the individual components. By fabricating materials with properties of the individual components and creating a material with novel properties that are specific to the composite and not to the individual components, a stronger and more useful material exists. As a result, polymer-nanotube composites have several useful applications such as structural supports for building, spacecrafts, and military aircrafts, non-linear optics, nano-wires, battery cathodes and ionics.
Various methods are known in the art to disperse carbon nanotubes in a polymer matrix. These known methods include: (1) solution mixing of polymer and carbon nanotubes; (2) a combination of sonication and melt processing; (3) melt blending and; (4) in-situ polymerization in the presence of nanotubes.
Advancements are known in the art providing methods of carbon nanotube dispersion in a polymer matrix, however the resulting nanocomposites produced to date exhibited limited transparency in the visible range.
There remains a need, therefore, for a method of preparation for nanocomposites that overcomes the shortcoming previously experienced with the dispersion of CNTs in polymer matrices. The resulting novel nanocomposites exhibit increased transparency and improved dielectric properties.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified need could be fulfilled.